Hexagonal Boron Nitride (BN) is used in many applications that require container material stable at high temperature or a high resistance electrical insulator. This material is also a very soft solid and has a tendency to flake and can be used as a solid lubricant similar to graphite.
Due to the significant industrial interest in BN, a very large number of reactions have been reported for its synthesis. Examples include a solid-gas phase reaction involving nitrogen or gaseous ammonia and silicon tetrachloride which has the disadvantages of being a very expensive reaction and requiring silicon tetrachloride which is difficult to make.
Another method involves the reaction of oxygen-containing boron compounds with cyanides. Such reactions take advantage of the strong reducing conditions created by the cyanides as well as their ability to provide nitrogen to the medium. Oxide compounds of boron most frequently used are B.sub.2 O.sub.3, H.sub.3 BO.sub.3 and Na.sub.2 B.sub.4 O.sub.7 which are reacted directly with NaCN or in conjunction with a sodium acceptor such as SiO.sub.2. This process has the disadvantage of having a hydrated reactant, the oxygen containing boron compound, which must be dried in order to remove the water of hydration. Additionally, some of the boron is converted to sodium borate thereby lowering the boron nitride yield. Also, if SiO.sub.2 is used as a sodium acceptor, it is difficult to purify the product since some sodium silicates are insoluble in water. Therefore, there is a need to provide a process for making boron nitride that is simple and efficient and inexpensive.